1. Field of the Invention
The present invention relates to novel hydroxyphenyl adamantanes which are useful as excellent materials in improving heat resistance and mechanical strength of epoxy resins, photosensitive resins, aromatic polycarbonate resins, or the like.
More specifically, the present invention relates to novel 1,3-bis(hydroxyphenyl)adamantanes and methods for the production thereof.
Further, the present invention also relates to novel 1,3,5-tris(4-hydroxyphenyl)adamantanes and methods for the production thereof.
2. Description of the Related Art
Hydroxyphenyl adamantanes, namely bisphenols and trisphenols having an adamantane ring skeleton, are desired to be highly heat resistant. One of such adamantane bisphenols already known is 1,3-bis(4-hydroxyphenyl)-5,7-dimethyl adamantane which is synthesized using 1,3-dibromo-5,7-dimethyl adamantane and phenol as raw materials as described in U.S. Pat. No. 3,594,427. Further, 1,3-bis(4-hydroxyphenyl)adamantane which is synthesized using 1,3-adamantane-diol and phenol as raw materials is described in Japanese Patent Application Laid-open No. 2000-143566. Furthermore, 2,2-bis(4xe2x80x2-hydroxyphenyl)adamantane which is synthesized using 2-adamantanone and phenol as raw materials is described in Japanese Patent Application Laid-open No. H10-130371.
However, these known adamantane bisphenols are those which have no substituent group in their hydroxyphenyl groups.
In recent years, characteristic requirements for compounds used as materials for resins such as epoxy resins, photosensitive resins, aromatic polycarbonate resins, or the like have been increasingly heightened and diversified and accordingly, also as for adamantane bisphenols, those having various substituent groups such as alkyl group substituents bonded to hydroxyphenyl groups are desired. However, such compounds and industrially advantageous methods for producing such compounds are not known.
On the other hand, as for compounds having three functional groups on an adamantane ring, 1,3,5-tribromo adamantane and a process for the production of adamantane-1,3-5-triol by using this adamantane as a raw material are described in Japanese Patent Application Laid-open No. H02-196477. Further, a higher carboxylic acid triester of adamantane-1,3,5-triol is described in Japanese Patent Application Laid-open No. H02-104553.
However, trisphenols in which three hydroxyphenyl groups are bonded to an adamantane ring and methods for producing such compounds are not known.
An object of the present invention is to provide novel 1,3-bis(hydroxyphenyl)adamantanes which are useful as raw material compounds for resins having high heat resistance, and methods for the production thereof. Further, an object of the present invention is to provide novel 1,3,5-tris(4-hydroxyphenyl)adamantanes which are useful as raw material compounds for resins having high thermal resistance, and methods for the production thereof.
Novel hydroxyphenyl adamantanes of the present invention are represented by the following general formula (1): 
wherein R is an alkyl group; cycloalkyl group or phenyl group; m is 0 or an integer 1 or 2; l is 0 or 1; when l is 1, hydroxy groups of substituted hydroxyphenyl groups at positions 1 and 3 are together in para-position; n is 0 or an integer 1, 2 or 3; and when l is 0, n is an integer 1, 2 or 3.
Further, 1,3-bis (hydroxyphenyl)adamantanes of the present invention are 1,3-bis(hydroxyphenyl)adamantanes represented by the following general formula (2) in which 4-hydroxyphenyl groups having substituent groups are bonded to positions 1 and 3 of the adamantane ring: 
In the general formula (2) above, R is an alkyl group, cycloalkyl group or phenyl group, n is an integer 1, 2 or 3, and m is 0 or an integer 1 or 2.
Further, these compounds can be efficiently produced by reacting a 1,3-adamantane-diol and substituted phenols in the presence of an acid catalyst under reaction conditions which are industrially feasible without difficulty.
Further, the abovementioned 1,3,5-tris(4-hydroxyphenyl)adamantanes of the present invention are 1,3,5-tris(4-hydroxyphenyl)adamantanes represented by the following general formula (3) in which 4-hydroxyphenyl groups with or without substituent groups are bonded at positions 1, 3 and 5 of the adamantane ring: 
In the general formula (3) above, R is an alkyl group, cycloalkyl group or phenyl group, n is 0 or an integer 1, 2 or 3, and m is 0 or an integer 1 or 2.
These novel 1,3,5-(4-hydroxyphenyl)adamantanes can be efficiently produced by reacting a 1,3,5-adamantane-triol and phenols in the presence of an acid catalyst under reaction conditions which are industrially feasible without difficulty.
Novel hydroxyphenyl adamantanes of the present invention are represented by the following general formula (1): 
In the hydroxyphenyl adamantanes represented by the general formula (1) above, R is an alkyl group, cycloalkyl group, or phenyl group, and when R is an alkyl group, the alkyl group is preferably a straight chain or branched chain alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Examples of such groups include a methyl group, ethyl group, propyl group, and butyl group. The propyl group or butyl group can be a straight chain or branched chain. Further, when R is a cycloalkyl group, a cycloalkyl group having 5 to 6 carbon atoms is preferable, and examples of such groups include a cyclopentyl group and cyclohexyl group. Further, m is 0 or an integer 1 or 2, preferably 0.
l is 0 or 1; when l is 1, hydroxyl groups of substituted hydroxyphenyl groups at positions 1 and 3 are together in para-position; n is 0 or an integer 1, 2 or 3; and when l is 0, n is an integer 1, 2 or 3. Further, when n is 2 or 3, R can be either the same or different, and accordingly hydroxyphenyl adamantanes of the present invention represented by the general formula (1) above can specifically be 1,3-bis(hydroxyphenyl)adamantanes represented by the general formula (2) above and 1,3,5-tris(4-hydroxyphenyl)adamantanes represented by the general formula (3) above.
Examples of the abovementioned 1,3-bis(hydroxyphenyl)adamantanes according to the present invention include 1,3-bis(2-methyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)adamantane, 1,3-bis(4-methyl-2-hydroxyphenyl)adamantane, 1,3-bis(5-methyl-2-hydroxyphenyl)adamantane, 1,3-bis(3-ethyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-isopropyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-s-butyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-t-butyl-4-hydroxyphenyl)adamantane, 1,3-bis(3,6-dimethyl-4-hydroxyphenyl)adamantane, 1,3-bis(3,5-dimethyl-4-hydroxyphenyl)adamantane, 1,3-bis(3,6-dimethyl-2-hydroxyphenyl)adamantane, 1,3-bis(2,3,5-trimethylhydroxyphenyl)adamantane, 1,3-bis(2,3,6-trimethyl-4-hydroxyphenyl)adamantane, 1,3-bis(3,4,6-trimethyl-2-hydroxyphenyl)adamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)adamantane, 1,3-bis(2-methyl-5-cyclohexyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)adamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-isopropyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3,6-dimethyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(2,3,5-trimethyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(2,3,6-trimethyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-cyclohexyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(2-methyl-5-cyclohexyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-phenyl-4-hydroxyphenyl)-5,7-dimethyladamantane, 1,3-bis(3-methyl-4-hydroxyphenyl)-4-methyladamantane, 1,3-bis(3-isopropyl-4-hydroxyphenyl)-4-methyl-adamantane, 1,3-bis(3,6-dimethyl-4-hydroxyphenyl)-4-methyl-adamantane, 1,3-bis(2,3,5-trimethyl-4-hydroxyphenyl)-4-methyl-adamantane, 1,3-bis(2,3,6-trimethyl-4-hydroxyphenyl)-4-methyl-adamantane, 1,3-bis(2-methyl-5-cyclohexyl-4-hydroxyphenyl)-4-methyl-adamantane, and 1,3-bis(3-phenyl-4-hydroxyphenyl)-4-methyl-adamantane.
Furthermore, examples of the abovementioned 1,3,5-tris(4-hydroxyphenyl)adamantanes according to the present invention include 1,3,5-tris(4-hydroxyphenyl)adamantane, 1,3,5-tris(3-methyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3-isopropyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3-s-butyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3,5-dimethyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3,6-dimethyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3-methyl-5-t-butyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(2,3,5-trimethyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(2,3,6-trimethyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3-cyclohexyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(2-methyl-5-cyclohexyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(3-phenyl-4-hydroxyphenyl)adamantane, 1,3,5-tris(4-hydroxyphenyl)-2-methyladamantane, 1,3,5-tris(3-methyl-4-hydroxyphenyl)-2-methyladamantane, 1,3,5-tris(3,5-dimethyl-4-hydroxyphenyl)-2-methyladamantane, 1,3,5-tris(3-cyclohexyl-4-hydroxyphenyl)-2-methyladamantane, 1,3,5-tris(3-phenyl-4-hydroxyphenyl)-2-methyladamantane, and 1,3,5-tris(4-hydroxyphenyl)-2,7-dimethyl-adamantane.
As for hydroxyphenyl adamantanes according to the present invention, 1,3-bis(hydroxyphenyl)adamantanes can be obtained by reacting a 1,3-adamantane-diol and substituted phenols in the presence of an acidic catalyst.
Further, 1,3,5-tris(4-hydroxyphenyl)adamantanes according to the present invention can be readily produced by reacting a 1,3,5-adamantane-triol and phenols in the presence of an acid catalyst.
As for 1,3-bis(hydroxyphenyl)adamantanes of the present invention, 1,3-adamantane-diols used as one raw material are represented by the following general formula (4): 
wherein m is 0 or an integer 1 or 2.
Examples of the abovementioned 1,3-adamantane-diols include 1,3-adamantane-diol, 5,7-dimethyl-1,3-adamantane-diol, 2-methyl-1,3-adamantane-diol, and 4-methyl-1,3-adamantane-diol. 1,3-adamantane-diol is preferable.
On the other hand, substituted phenols used as the other raw material in the present invention are represented by the following general formula (5): 
wherein R and n are as defined in the general formula (2) above.
Examples of the compounds of the general formula (5) above include 2-methylphenol, 2-ethylphenol, 2-isopropylphenol, 2-s-butylphenol, 2-t-butylphenol, 3-methylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 2,6-diisopropylphenol, 2,6-di-t-butylphenol, 2-methyl-6-t-butylphenol, 3,5-dimethylphenol, 3-methyl-6-t-butylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2-cyclohexylphenol, 3-methyl-6-cyclohexylphenol, 2-phenylphenol, and 2-isopropyl-6-phenylphenol.
Further, as for 1,3,5-tris(4-hydroxyphenyl)adamantanes of the present invention, 1,3,5-adamantane-triols used as one raw material are represented by the following general formula (6): 
wherein, m is 0 or an integer 1 or 2.
Examples of the 1,3,5-adamantane-triols include 1,3,5-adamantane-triol, 2-methyl-1,3,5-adamantane-triol, 7-methyl-1,3,5-adamantane-triol, and 2,7-dimethyl-1,3,5-adamantane-triol. Of these triols, 1,3,5-adamantane-triol is preferable.
Phenols used as the other raw material in the present invention are represented by the following general formula (7): 
wherein R and n are as defined in the general formula (3).
Examples of the abovementioned phenols include phenol, 2-methylphenol, 2-ethylphenol, 2-isopropylphenol, 2-s-butylphenol, 2-t-butylphenol, 3-methylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 2,6-diisopropylphenol, 2,6-di-t-butylphenol, 2-methyl-6-t-butylphenol, 3,5-dimethylphenol, 3-methyl-6-t-butylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2-cyclohexylphenol, 3-methyl-6-cyclohexylphenol, 2-phenylphenol, and 2-isopropyl-6-phenylphenol.
In the reaction of the abovementioned 1,3-adamantane-diol or 1,3,5-adamantane-triol and phenols, the ratio of the 1,3-adamantane-diol or 1,3,5-adamantane-triol to the phenols is in the range of 3-30, preferably 6-10 by mol.
In the method for the production according to the present invention, an acid catalyst is used in the reaction. Examples of such an acid catalyst include inorganic acids such as hydrogen chloride, hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and p-toluene sulfonic acid; carboxylic acids such as acetic acid and propionic acid; heteropolyacids; and cation exchange resins. Of these acids, strong acids including inorganic acids such as hydrochloric acid and sulfuric acid, sulfonic acids such as p-toluenesulfonic acid, heteropolyacids, highly acidic cation exchange resins are preferable, and in particular, p-toluenesulfonic acid is preferable in terms of reaction velocity and reaction selectivity.
p-Toluenesulfonic acid used is generally a monohydrate. The amount of p-toluenesulfonic acid generally ranges from 30 to 80% by mol, preferably 40 to 60% by mol, of a raw material, i.e., a 1,3-adamantane-diol or 1,3,5-adamantane-triol. In the reaction of a 1,3-adamantane-diol or 1,3,5-adamantane-triol with phenols in the presence of an acid catalyst, the reaction can be carried out either with or without a reaction solvent. Examples of preferable reaction solvents are aromatic hydrocarbons such as toluene. The amount to be used generally ranges from 5 to 50% by weight of a raw material, i.e., phenols. Further, the reaction temperature generally ranges from 60 to 200xc2x0 C., preferably 70 to 150xc2x0 C., more preferably 80 to 110xc2x0 C. Under these reaction conditions, the reaction generally completes within about 1 to 100 hours with 1,3-adamantane-diols. Further, the reaction generally completes within about 10 to 200 hours with 1,3,5-adamantane-triols.
After the reaction, an aromatic hydrocarbon solvent such as toluene and xylene is added to the reaction mixture thus obtained if necessary, and the reaction mixture is dissolved, after which the solution is neutralized by adding an aqueous solution of alkali such as sodium hydroxide or potassium hydroxide with stirring. Next, the water layer is separated and removed from the neutralized oil-water mixture to obtain the oil layer which contains the target product. The targeted 1,3-bis(hydroxyphenyl)adamantane or 1,3,5-tris(4-hydroxyphenyl)adamantane is crystallized from the oil layer thus obtained, filtered, and isolated to obtain crude crystals of the target product.
Further, if necessary, a pure product of the target product can be obtained by the purification procedure such as recrystallization.